<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>导航栏动画</title>
    <link rel="stylesheet" href="css/style.css">
</head>

<body>

    <nav class="nav">
        <input type="radio" name="nav-item-opt" id="nav-item-opt-1" checked>
        <label class="nav-item" for="nav-item-opt-1">HTML</label>

        <input type="radio" name="nav-item-opt" id="nav-item-opt-2">
        <label class="nav-item" for="nav-item-opt-2">CSS</label>

        <input type="radio" name="nav-item-opt" id="nav-item-opt-3">
        <label class="nav-item" for="nav-item-opt-3">JavaScript</label>

        <div class="tracker"></div>
    </nav>

</body>

</html>